"Washington on the Potomac" is a personal homage to the nation's capital, where McCullough lives and works. Woodrow Wilson is the only president to retire in Washington, where he makes his last public appearance on Armistice Day 1923, hailed by 20,000. McCullough often wonders about his wife being de facto the first woman president, and what the people in the crowd that day think about their former commander in chief - the day The New York Times headlines Hitler rallying near Munich. McCullough walks past the Wilson house some mornings at a brisk 120 steps a minute, like Harry S. Truman, about whom he is writing. Washington is a wonderful, well-scaled, humane city. McCullough likes the old landmark hotels, finds the National Gallery alone sufficient reason to live there, and extols its making room for nature. From the George Washington Parkway, the view of...